CASK is a Ca2+/CaM-dependent serine protein kinase belonging to the family of Membrane Associated Guanylate Kinases (MAGUK), all of which contain PDZ (PSD-95, Dlg, Zo-1), SH3 (Src Homology 3), and GK (guanylate kinase) domains. These domains function as protein scaffolding domains at cell-cell junctions and function to cluster channels and receptors. Previous work on CASK has focused on its role in the central and peripheral nervous systems, epithelial cell junctions, and neuromuscular junctions. However, recent work has suggested a role for CASK in Drosophila oogenesis. Specifically, a recent RNA interference screen identified CASK as a contributor to border cell migration. Border cell migration is a process by which two specialized polar cells are carried by 8-10 surrounding “border cells” from the anterior of the egg chamber to the oocyte where they form the micropyle, the site of sperm entry in the Drosophila egg. This work suggests that CASK may have an important role in development of the fully mature female egg. Moreover, because border cell migration is used as a model of collective cell migration, studies of CASK protein function and binding partners can lead to novel insights into the mechanisms that regulate how cells move en masse. As a means of establishing a general framework for future investigations into CASK’s role in Drosophila oogenesis, CASK isoform expression and the affect of CASK knockout on fecundity and fertility were assayed. To establish which CASK isoforms are expressed in ovaries, reverse-transcriptase PCR (RT-PCR) was conducted on total fly and ovary extracts from the wild-type w1118 fly line using isoform specific primers to all seven Drosophila CASK isoforms (CASK-A, -B, -D, -E, -F, -G, -H). This work has confirmed the expression of CASK-A, -B, -G, -H and –E in Drosophila ovaries; work confirming the presence or absence of isoforms –D and –F is still underway. In order to assess a possible role for CASK in fecundity and fertility we took advantage of an available CASK knockout fly line. Fecundity was measured by counting the number of eggs laid by individual CASK knockout female flies at 24 and 48 hours (n= >30 for both wild-type and knockout fly lines). These results demonstrated that CASK knockout does not affect the rate of egg laying in female flies. Further work will assess whether CASK knockout affects fertility by measuring embryo viability. This work represents a vital first step in the characterization of CASK protein function in Drosophila oogenesis and the process of border cell migration.